1. Field of the Invention
This invention relates to a magnetic recording and/or reproducing apparatus of the cassette type and, more particularly, to a tape transport system for use in such an apparatus.
2. Description of the Prior Art
Recently a magnetic recording and/or reproducing apparatus which employs a magnetic tape cassette for making a recording and/or reproduction of optical images (hereinafter called as a cassette type VTR) has a tendency to make it small, particularly a guide drum having a rotating magnetic head for recording and/or reproducing and a tape cassette are made to have a small size.
Heretofore, as a cassette type VTR of 2 head-helical-scanning type, such system has been known that a pair of tape extracting means are positioned at an inside of a tape within a cassette as said cassette is loaded, and said pair of tape extracting means are made to proceed from said position to outside of said cassette in a parallel manner sandwiching the guide drum so that the tape is wrapped about the guide drum in a tightly contacting manner, and at a time of loading the cassette a pinch roller is made to pressure contact with a capstan positioned inside the tape within said cassette from outside of the cassette sandwitching the tape therebetween for driving the tape to run the same within the cassette. And since a cassette type VTR with said kind of system has an arrangement that a capstan is made to proceed into a cassette as the cassette is loaded for driving the tape to run the same within the cassette, unless a width in a lengthwise direction of the cassette is made sufficiently large compared to a diameter of a guide drum, the driving of the tape to run the same will be very difficult thus it is apparently disadvantageous in making a size of a cassette small, therefore, it is difficult to make a size of a total apparatus small due to a size of the cassette.
On the other hand, as a cassette type VTR of a 2-head-helical-scanning type, such system has been known to date beside the above-mentioned system that tape extracting means and a pinch roller are positioned at an inside of a tape within a cassette as the cassette is loaded and said tape extracting means and pinch roller are integrally shifted in a rotating manner around a guide drum from said position so that the tape is wrapped about the guide drum in a tightly contacting manner and the pinch roller is made to pressure contact with the capstan placed near said tape loading position sandwiching the tape therebetween at the tape loading position thus driving the tape to run the same. And in this latter type of cassette VTR, the above-mentioned disadvantages seen in the former type of cassette VTR are eliminated, but on the other hand since the latter type has an arrangement that a space between the cassette and the guide drum is apt to become large and at the same time, the pinch roller is rotatingly shifted around the guide drum together with the tape extracting means to the tape loading position, a sufficient space for shifting of the pinch roller has to be secured around the guide drum. Therefore, a space around the guide drum increases which is apparently disadvantageous for making a size of a total apparatus small. Thus, even if the special feature of said former type of cassette VTR and that of the latter type of cassette VTR are combined, an object of making a size of a cassette and that of a total apparatus small has been quite difficult to be achieved.
Further, in the former type of 2-head-helical-scanning VTR, a pin about vertical relatively against a cassette supporting plane (base plate) and a relatively inclined pin provided on a pair of tape extracting means are positioned at an inside of a tape within a cassette as the cassette is loaded and said pair of tape extracting means are shifted from said state to outside of the cassette so that the tape is pulled out of the cassette in about parallel manner against said cassette supporting plane, further said pair of tape extracting means are made to proceed in a parallel manner sandwiching a guide drum which has a pair of recording and/or reproducing magnetic heads facing to each other in 180 degree and are so provided as being relatively inclined with a prescribed angle against the cassette supporting plane, so that the tape being pulled out is wrapped about an outer circumference of the guide drum in a tightly contacting manner for an extent of 180 degree or more in an about parallel manner against the cassette supporting plane for making a recording and/or reproducing of optical images. And these conventionally known types of a cassette VTR has such an arrangement that the vertical pin and the inclined pin at the tape extracting means have their relative positions so fixed on a base plate of the extracting means that the inclined pin is always positioned at the guide drum side, while the vertical pin is positioned at an outside, and the vertical pin and the inclined pin are shifted at a time of tape loading and tape unloading in such parallel manner that their relative positional relationship on said base plate are unchanged. Therefore, in a cassette VTR with such arrangement since a vertical pin and an inclined pin are shifted together in a parallel manner, a relatively large space is needed around a guide drum for shifting of tape extracting means, therefore, it is apparently disadvantageous for making a size of an apparatus small. That is, in general, a total width erasing head, and an audio signal and control signal recording and/or reproducing head, etc. are fixedly positioned near a guide drum, and tape extracting means are shifted between the guide drum and said fixed heads, and in order to secure a sufficient space for shifting of the tape extracting means said fixed heads must be positioned with a large distance from the guide drum, thus it is disadvantageous for making a size of an apparatus small. Especially, conventionally known type of cassette VTR of said kind is so made that a positional control of the tape extracting means is not so extensively made during a shifting of said extracting means and the tape extracting means are caught by catching means at a tape loading position thereby making exact positioning of the same. Therefore, said tape extracting means apt to become unstable in a shifting process before it reaches a tape loading position, thus a space for its shifting needs to be that much larger.
Also generally speaking in a magnetic recording and/or reproducing apparatus using a cassette type tape for recording and/or reproducing optical images, a tape is pulled out of a loaded tape cassette by tape extracting means and is sent to a guide drum having a rotating magnetic head for recording and/or reproducing optical images thus making a recording and/or reproduction of optical images. Therefore, it is necessary that as the cassette is taken out while the tape extracting means are returned to a direction of the cassette the tape is returned to within the cassette absorbing a sag or a slack of the tape generated by a change in a tape running path at this time (that is unloading). And for that what has been done hitherto is that independent rotating means which is used solely to absorb the sag or slack of the tape at said tape unloading are provided and a tape reel is driven by said rotating means for absorbing the sag or slack of the tape at the time of tape unloading, or a driving system for fast forwarding of tape or for quick rewinding of tape which is provided at almost all types of apparatus of this kind is activated also at the time of tape unloading so that the tape reel is driven by said high speed running drive system for absorbing the sag or slack of the tape at the time of tape unloading.
Now, as said two different types of methods are compared, an additional element such as independent rotating means which is used solely for absorbing the sag or slack of the tape in tape unloading is not necessary in the latter method, therefore number of components will be less and an arrangement of a reel driving system is simplified. But, while it has said advantages the same method has disadvantages that the tape reel is driven at the time of tape unloading in a same manner as in a high speed running drive of tape as in fast forwarding or quick rewinding of the tape, therefore a taking up torque of the tape reel becomes excessively large and its taking up speed will be remarkably high compared to a speed of growing of the sag or slack of the tape along with a return of the tape extracting means to the tape unloading position, causing large stress on the tape.
In order to eliminate said disadvantages for example, reduction gear means are provided in a high speed tape running drive mechanism mentioned above or its driving motor is run with a reduced speed and the like can be conceived. But in any event it creates complication of an arrangement of a reel driving mechanism or complication of an arrangement of a motor control circuit, which is disadvantageous in making a size of apparatus small.